1. Field of the Invention
The invention relates to electrical power systems, and more particularly, to power systems having modules positioned beneath access flooring structures and the like.
2. Description of Related Art
The use of computers, sophisticated telecommunications equipment and other electronic devices is continuing to rapidly increase in commercial, industrial and other office environments. As a result, the importance of efficiently supplying power throughout these environments is also increasing. In particular, the use of modular office systems, with movable workstations and interior walls, has led to electrical systems far different and more sophisticated than the conventional designs comprising single or double unit electrical receptacles mounted in stationary walls, with the receptacles energized from incoming power supplies with cables extending through wall interiors. Such conventional single or double unit receptacles, particularly when used with modular office systems, were often located a substantial distance from electrical devices to be energized and would cause unsightly and sometimes dangerous arrays and result in entanglements of the electrical cords connected to the devices. Thereafter, pluggable units having a number of receptacles and a common power source cord to be plugged into the conventional utility outlet started to be used. Again, however, such units result in unsightly and entangled arrays of electrical device cords.
With the growth of the use of electrical power and modular office systems, it became known to employ removable wall panels or the like (which defined the workstation areas), with the panels or other structures having a raceway area for accommodating electrical wiring and electrical junction blocks near the floor or otherwise near the locations to be energized. Typically, junction blocks were mounted within the raceway areas by attaching them with various types of structural arrangements. During the past two decades, a substantial number of issued patents have been directed to concepts associated with these raceways and means for mounting electrical receptacles within the raceways.
Although the concept of employing raceways and electrical receptacles within modular wall panels and the like presented a substantial advance in electrical power supply design, this type of design does not provide a complete solution for all office system arrangements. For example, such panels can be relatively expensive and require a substantial number of different types of electrical components. Further, the particular electrical components to be employed can be dependent on the specific office system design. For example, many of these electrical system arrangements require different components dependent upon whether outlets are to be used on one side of a removable panel or the other side. Still further, many of these systems include relatively complex and expensive components to interconnect electrical power among various wall panels.
In addition to the foregoing problems, these electrified panels do not provide a complete solution to efficiency and aesthetics of power supply design when a more conventional office system design employs stationary walls with more permanent and fully enclosed offices. On the other extreme, in completely open office or “bullpen” design arrangements, no walls, removable or otherwise, are employed and the electrical system designer is again left with significant design problems.
In view of all of the foregoing, electrical system designers are again considering the use of electrical receptacles and similar electrical devices beneath access flooring. Such flooring arrangements allow power and signal cables to be placed beneath the floor in positions which do not interfere with the placement of walls or furniture. Further, such arrangements do not require any walls whatsoever, as required with raceways and receptacles mounted within removable walls. With the use of access flooring, the power and signal cables, along with other appropriate electrical devices, can be moved as the modular offices or other office design arrangements are modified.
Floor mounted devices for providing electrical service have been known for several decades. Early devices typically employed power supply cables extending underneath permanent flooring and interconnected to junction boxes or the like. Electrical receptacles would be mounted by some means within the junction boxes and electrically connected to the receptacle outlets.
For example, Stas, U.S. Pat. No. 2,996,566 discloses a floor-type outlet box for use within concrete flooring. The outlet box includes a duplex receptacle positioned so that the receptacle outlets extend vertically upward slightly beneath the floor level. A cover plate is hingedly mounted to the box and capable of being sealed to provide a water-tight housing flush with the concrete floor. Another, still earlier, disclosure of a junction box having electrical outlets for use in concrete floors is set forth in Buchanan, U.S. Pat. No. 1,928,198. The Buchanan patent is primarily directed to an arrangement for adjusting the position of the outlet box after the concrete floor is poured so as to compensate for any undesired displacement.
Several of the known arrangements for providing electrical receptacles in floors include arrangements for selectively positioning the receptacles between exposed and concealed positions. For example, Press, U.S. Pat. No. 3,622,684 discloses a floor receptacle mounting unit having electrical receptacles which can be rotated to a position in which the receptacles are exposed above the level of the floor or, alternatively, rotated to positions in which the receptacles are concealed below the floor level. Myers, U.S. Pat. No. 3,433,886 discloses an electrical junction box to be mounted flush with a floor. The junction box adjustably mounts an electrical service or receptacle box which is recessable below the floor surface through the use of adjusting machine screws. Other floor mounted electrical junction boxes and receptacles are shown in the following references: Kelly, U.S. Pat. No. 3,395,243; Wiesmann, U.S. Pat. No. 2,738,892; Fuller, U.S. Pat. No. 3,975,074; Guerrero, U.S. Pat. No. 2,811,574; MacLeod, Jr., U.S. Pat. No. 3,131,512; and Dubreulio, U.S. Pat. No. 3,794,956.
With respect to the previously cited references, most of these references are directed to floor mounted electrical receptacles and junction boxes to be mounted in permanent flooring. However, with the increase in use of modular offices, and for various other design and structural reasons, the use of access flooring is becoming more widespread. Such access flooring also allows the positioning of junction boxes and incoming power and signal cables to be placed beneath the floor after or during the design of the office systems (modular or otherwise) to be employed within the commercial or industrial environment. Such access flooring also allows for power and signal cables to be placed beneath the floor in a position which will not necessarily interfere with the placement of walls or, for that matter, furniture placement following complete office design. In addition, the use of such access flooring allows for junction boxes, electrical outlet boxes, power and signal cables to be selectively moved as the office systems are rearranged.
In known systems for utilizing electrical power with access flooring, power and signal cables are interconnected between incoming power supplies and junction or electrical receptacle boxes referred to herein as access floor modules. Appropriate office equipment is directly connected to receptacle outlets within the access modules which are designed specifically for receiving the receptacle outlets.
An example of a known access floor module is disclosed in Brownlie et al., U.S. Pat. No. 5,122,069. With reference to the drawings and the numerals disclosed in the Brownlie et al. patent, FIGS. 1–4 illustrate an access flooring module to be mounted in an opening 4 provided in an access floor. The module 2 is movable between an open position (FIG. 3) and a closed position (FIG. 4). Recesses 24 are provided so as to receive electrical components such as power sockets 34 or signal sockets 36 shown in FIG. 1. Metal plates 25 (shown in FIG. 2) selectively provide electrical contact with electrical components to be utilized with the module 2. In an alternative embodiment of the Brownlie et al. patent, FIG. 12 depicts interconnection of high tension cables 240 and low tension cables 241 to the rear of an alternative module 200. The high tension cable 240 is secured through a hard wire bracket 209, with the low tension cable 241 secured through a data bracket 211. Cable ties 242 are utilized to secure the cables to the rear of the module.
Although the prior art shows a number of designs for floor-mounted boxes capable of mounting electrical receptacles, an important aspect of floor-mounted arrangements is the overall “system.” The overall system includes all of the junction boxes, electrical receptacle boxes and outlets, and the requisite cabling, including the means for interconnection of cabling. For example, if the system requires cables of different types with respect to lengths, connectors, and other structural considerations, the system designer's job is more complex, since the designer must essentially have a final system design before ordering the requisite cabling. Although an inventory of various cables may be ordered and stored, such an inventory may be expensive, take up valuable storage space and involve components which are never used. Still further, if a voluminous inventory is not desired, the designer must have exact details as to positioning of electrical outlets, system dimensions and other layout information before undertaking the process of ordering the cabling.
Other design and assembly issues for these types of electrical systems relate to system components other than cabling. For example, such systems may utilize one type of component for a junction box, and another type of component for mounting electrical receptacles. Again, such a structure suffers from the same problems previously described with respect to requiring various types of cables for the overall system.
In addition to issues associated with cabling, junction boxes and receptacle mounting structures, the means for interconnecting system components is also important. For example, if the interconnection of cables to other cables, or to junction boxes and the like, requires hard-wired connections, problems arise with respect to both design and assembly. More specifically, assembling electrical components beneath a floor structure by means of screws and bolts is an arduous task, even for the most skilled electrician.
In view of all of the foregoing, it would be advantageous to provide an electrical access floor system with substantial interchangability of components, reduction in the number and types of different components, and ease of interconnection of components and general assembly.